The present invention relates to flash flow processing, and, more particularly, to improvements in melt spin processing machines to enhance process capability.
Various machines have been designed for spinning feedstock materials, particularly sugar, while at the same time applying heat to the feedstock. The materials may be introduced to a spinner assembly within the spinning machine in molten form or, alternatively, introduced in solid form and heated to the flow point or subjected to flash-flow just prior to being spun out from the spinner assembly.
U.S. Pat. No. 4,872,821 discloses a spinning machine that is particularly designed for spinning cotton candy. The machine includes a spinner head having slotted, cylindrical walls and heating elements adjacent to each wall. Sugar in solid form is introduced into the spinner head and propelled against the heating elements where it is made flowable and spun out through the slots where it solidifies into the floss-like material known as cotton candy.
Various other machines have been designed over the years for spinning cotton candy. One such machine is disclosed in U.S. Pat. No. 3,930,043. This machine includes a helical resistance heating element positioned within a finely perforated shell. The heating element is supported against the inner wall of the shell by spacer elements. As the shell spins, molten sugar moves through the perforations. Similar machines are disclosed in U.S. Pat. Nos. 3,073,262 and 3,070,045.
Still another machine for spinning substances is disclosed in commonly owned, co-pending U.S. patent application Ser. No. 07/954,257 to Fuisz. The application discloses a spinner head including a heating element which defines a narrow, elongate opening providing a substantially non-tortuous path through which feedstock material subjected to flash-flow is projected. Various other spinning machines of the prior art are referenced therein.
A basic spinning machine includes a spinning head with a heating element arranged circumferentially therearound. Sugar is introduced to the spinner head and dispersed along the heating element. Heat from the heating element thereby changes the physical structure of the sugar sufficiently to permit the sugar to flow through openings and form the floss product. In early models, heat is applied as the spinner head rotates whereby the floss product is generated. The early models had virtually no means for controlling the various factors that strongly influenced the quality of the spun product. These factors include: the temperature of the heating element and therefore the amount of power directed to the heating element, the size of the opening through which feedstock material is projected, and feed rate at which the feedstock material is fed into a feeder assembly for processing by the spinner head.
In the more recent models, methods of controlling the several above-mentioned factors have been implemented. For example, commonly owned, co-pending U.S. patent application Ser. No. 08/049,773 discloses a temperature feedback control method and apparatus to precisely control heating of the feedstock material during the flash flow process. Such temperature control ensures more consistent spin processing operation and a higher quality spun product.
A method for attempting to control the volume of processing material within a spinner head of a melt spin machine is disclosed in U.S. Pat. No. 3,930,043. The rate that sugar is fed to the spinner head is mechanically controlled by detecting a physical displacement of a portion of the sugar present within the head and shaped according to a vortex formed by the spinning head. More or less sugar is fed into the rotating head according to the detected physical displacement of the sugar therein. This method of feed rate control, however, is inexact. Shifts in the melt spin machine may shift the detectable mass rendering inaccurate displacement detection. Accordingly, the mass of sugar (or feedstock material) present in the spinner head may exceed or fall short of an amount commensurate with the spinning machine's ability to smoothly process it. Carbonization of the heating element and product burning are the likely result.
It is therefore an object of this invention to provide a material processing method and apparatus for flash flow melt spin processing with feed rate control characteristics capable of preventing overloading of the processing head with an excessive volume of processing material.
A still further object of the invention is to provide a material processing apparatus for flash flow melt spin processing having feed rate control achieved using a detected weight of the processing head to determine the flow rate of feedstock material into the processing head necessary for producing a high quality product.